Electrical radiant heating unit



Oct. 7, 1969 E. F. KELM ELECTRICAL RADIANT HEATING UNIT Filed Sept. 15, 19*? EVERETT- EI VKEZLM AGENT United States Patent ELECTRICAL RADIANT HEATING UNIT Everett F. Kelm, Corning, N.Y., assignor t0 Corning glass Works, Corning, N.Y., a corporation of New or t Filed Sept. 13, 1967 Ser. No. 667,435 Int. Cl. 1165b 1/00 US. Cl. 219-342 5 Claims ABSTRACT OF THE DISCLOSURE An electrical resistance heating unit for radiant heating, or for broiling, grilling or similarly cooking foods, such unit including a section of curved glass or vitreous material which contacts only the'tips or crests of the undulations of a sinuously wound electrical heating element thereby permitting such unit to glow rapidly to provide an early indication of the on condition of the unit following the energization thereof.

Background of the invention The present invention relates to the field of art of electrical heating units to be used for radiant heating or cooking purposes. The electrical resistance heating element employed in the heating unit of the invention is arranged so that, upon the supplying of electrical power thereto, the heating element glows orange or bright red substantially immediately to provide a visual indication of the on condition of such element.

There is disclosed in Letters Patent of the United States 2,870,316, issued Jan. 20, 1959, to H. D. Ferguson, Jr. and entitled Heaters, an electrical plate type or so-called surface heater including an electrical lamp for providing visual indication of the on and off condition of the heating element or elements of the heater. The plate of such plate type heater comprises a glass plate which is or a portion of which is entirely light transmissive. Such lamp is located beneath such plate and the indication provided by the lamp is disclosed through the plate. The heating element or elements of the heater are held against the lamp surface of said plate and, especially when such element or elements are energized under simmering conditions as mentioned in the patent,

there is a delay before the elements glow sufficiently to provide an on indication of the heater even if the element or elements ever do glow to a sufficient amount to provide the desired indication under said conditions. Such delay in or absence of sufficient glow of the element or elements is at least partially the result of the generally overall physical contact thereof with said glass plate and the resultant rapid transfer of heat from said element or elements to such plate by conduction. Accordingly, said electrical lamp is used to provide an indicating means which is immediately responsive to the energized or deenergized condition of said heating element or elements. With such considerations in mind, the electrical radiant heating unit of the present invention was conceived in order to eliminate the necessity of a separate component, such as the electrical lamp of the cited patent, for the purpose of providing an immediate indication of the energized condition of the heating unit when it is first energized. The heating unit herein disclosed is intended for use as a radiant heating or cooking unit rather than as a so-called surface heater as in said patent.

Summary of the invention In practicing the invention, there is provided a heating element comprising a length of a sinuously or serpentinely wound electrical resistance heater wire which is disposed in an enclosure including an arcuate portion of a length of glass or vitreous tubing, such tubing substantially corresponding in length to said length of sinuously wound heater wire. The heater element comprising said length of wound wire contacts said portion of glass tubing only at the tips or crests of the undulations of the sinuously or serpentinely wound wire and, therefore, a very minimum amount of heat is transferred to said portion of glass or vitreous tubing by conduction thereto. Thus, upon energization of said heater element, it rapidly glows to provide an on or energized indication of the element.

Brief description of the drawings In the drawings:

FIG. 1 comprises a top plan view of a heating unit employing the invention, the center section of such unit being omitted for purposes of simplification of the drawing; and

FIG. 2 is a cross-sectional view of the unit of FIG. 1, such view being taken along line 2-2 of FIG. 1.

Similar reference characters refer to similar parts in each of the figures of the drawings.

Description of the preferred embodiment Referring to the drawings in detail, there is illustrated an elongate heating unit 10 comprising a trough-like housing member 11 preferably made of metal and embodying a relatively shallow chamber or channel 11c. A springy, spongy or resilient electrical and thermal insulation material 20 is disposed in and substantially fills channel and one surface of a serpentinely or sinuously wound, or undulated electrical resistance heater element or wire 13 is placed against the otherwise exposed top surface of material 20.

An elongate curved or concavo-convex piece or section of at least a somewhat transparent, electrically insulating, heat transmissive and heat shock resistant vitreous material or glass 12 is positioned in channel 110 of member 11 adjacent the top opening of such channel and the longitudinal edges such as 11a of member 11 are bent over the longitudinal edges of the section of glass 12 to hold it firmly against lateral movement within channel 110. Member 11 further includes, at the ends of the longitudinal edges such as 11a of such member, tab portions such as 1117 which are bent over the ends of glass section 12, adjacent said longitudinal edges thereof, to hold such glass section against longitudinal movement within channel 110 of member 11. The curved section of glass 12 may, for example, comprise an elongate arcuate portion of a length of glass tubing formed from a so-called high silica glass. VYCOR brand tubing sold by Corning Glass Works, Corning, N.Y., is one example of such glass tubing. The chord of such arcuate portion of glass tubing is substantially equal to the width of the top opening leading into channel 11c embodied in housing member 11.

Heater element or wire 13 contacts or is contacted by the concave surface of the section of glass 12 only at the tips or crests of the undulations of such wire, and as shown in FIG. 2, material 20 is compressed by heater element 13 to such an extent that the inherent resiliency of such material causes a slight bowing of such heater element and thereby, firm contact between said crests of the undulations of the heater element and the points on glass section 12 contacted thereby. Element 13 is thus held firmly in channel 110 of member 11.

The right and left hand ends (viewing FIG. 1) of heater element 13 are provided with electrical contact members or connections 14 and 15, respectively, which are crimped about such ends of element 13, or otherwise secured thereto, to provide adequate and suitable electrical circuit connections to the respective ends of element 13. First ends of wires or electrical conductors 16 and 17 are connected to contact members 14 and 15, respectively, in any suitable manner, such as by soldering, for example, and element 13 can be energized by connecting the second ends of Wires 16 and 17 across first and second terminals of a source of electrical current of a voltage and capacity selected in accordance with the electrical resistance of element 13 to provide rapid heating thereof. However, for purposes of simplification of the drawings said source of electrical current is not shown therein.

The right and left hand ends of channel 110 in member 11 are closed by plugs 18 and 19, respectively, of a suitable thermal and electrical insulating material which may be similar to material 20 and which may, for example, be stuffed into the ends of channel 11c about contact members 14 and 15 extending from the ends of such channel.

In use, the heating unit is disposed in a suitable radiant heating or broiling enclosure and, as previously mentioned, the unit is energized by connecting units 16 and 17 across a suitable source of electrical current. Since the section of glass 12 only contacts or is contacted only by the tips or crests of the undulations of heater element 13, there is a very minimum of conductive heat transfer from such element to glass section 12 and the heater element reaches a visible glowing temperature substantially immediately following the supply of electrical power across the ends of the element. Such substantially immediate glow of the heater element gives visible indication to the housewife, or other user of an appliance incorporating such an element, that the appliance is in its energized or on condition. There is, therefore, no waiting period for assurance that the appliance is operating and the user thereof, after perceiving said visual indication, can turn to other tasks substantially immediately following the switching of the appliance to its on condition.

Although there is herein shown and described only one specific example of a heating unit embodying the invention, it will be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of the invention.

What is claimed is:

1. An electrical heating unit comprising:

(a) a metal housing member embodying a relatively shallow open-topped chamber;

(b) a curved section of transparent, electrically insulating, heat transmissive and heat shock resistant glass disposed and secured in said chamber adjacent to and covering the top opening thereof;

(c) an undulated electrical resistance heating element disposed in said chamber and below said section of glass with only crests of the undulations of such element contacting said section of glass;

(d) a springy, electrical and thermal insulation material substantially filling that portion of said chamber below said heating element and compressed to a degree by such element; and

(e) electrical contact members on the ends of said heating element for connecting such element across a source of electrical current.

2. An electrical heating unit in accordance with claim 1 and in which,

(a) said housing member has substantially a shape of an elongate open-ended trough and said chamber therein is the channel in such trough;

(b) said curved section of glass is an elongate arcuate portion of a length of glass tubing; and

(c) said heating element is an elongate length of sinuously wound electrical resistance Wire, the tips of the sinuous windings of such wire being said crests of said undulations of the heating element.

3. An electrical resistance heating unit for radiant heating or cooking, such unit comprising:

(a) an elongate trough-like housing member employing a trough-like channel including an opening leading into said channel;

(b) a resilient,'electrical and thermal insulation material substantially'filling said channel;

(c) an elongate serpentinely wound electrical resistant heating element disposed against and extending along the length of the otherwise exposed surface of said material, the width of such heating element being less than the width of said opening leading into said channel;

(d) an elongate, concavo-convex section of electrically insulating and heat transmissive glass disposed over said heating element and secured in said channel adjacent to and covering said opening therein with points on the concave surface of the glass firmly contacting the tips of the serpentine windings of said heating element with a force sufficient to depress such element and impart compression to said resilient material; and

(e) means connected to the ends of said heating element and extending externally of said housing member for supplying electrical power across such element.

4. A heating unit in accordance with claim 3 and in which said section of glass is an arcuate portion of a length of glass tubing, the chord of such arcuate portion being substantially equal to said width of said opening leading into said channel embodied in said housing member.

5. An electrical resistance heating unit comprising:

(a) an enclosure including a metal member embodying a shallow open-topped chamber and a concavoconvex piece of vitreous material disposed adjacent to and covering the top of such chamber with its convex surface protruding from the open top of the chamber;

(b) a resilient insulating material below said vitreous material substantially filling the remainder of said chamber;

(c) an undulated electrical heating element disposed between said material and said piece of vitreous material with only the crests of the undulations of such element contacting the concave surface of such vitreous material; and

(d) electrical connections to points on said heating element for supplying electrical current thereto.

References Cited UNITED STATES PATENTS 2,870,316 1/1959 Ferguson 2l9453 3,067,315 12/1962 Hurko 338--292 X 3,086,101 4/1963 Scofield 219-464 X JOSEPH V. TRUHE, Primary Examiner M. C. FLIESLER, Assistant Examiner US. Cl. X.R. 

